One of the most common causes of death in the world is vascular illnesses, particularly cardiac infarction. This is caused by arteriosclerosis, a disease of the coronary vessels. Due to deposits of arteriosclerotic plaque “blockage” of coronary vessels occurs. If a coronary angiography indicates stenosis of the coronary vessels, that causes angina pectoris, that restricts functional capacity and/or threatens a patient, then, at present, a decision is made depending on the features of the case as to whether a bypass operation or a balloon dilatation (Percutaneous Transluminal Coronary Angioplasty=PTCA) is to be performed. In the majority of cases these days a PTCA is carried out. To do this, the narrow parts of the coronary vessels are dilated using a “balloon catheter”. A saline solution with 8-15 ATM is forced into the balloon for this balloon dilatation. So that the narrowed vessels do not return to their original condition after the dilatation, a stent has, since the nineties, been inserted into the expanded section of the vessel. A description of a stent is, for example, given in documents DE 299 24 228 A1, DE 200 09 204 A1 and EP 08 78 174 A1.
Up to now, the diagnosis and therapy of the stenosis described above required several process steps. Most frequently, the diagnosis of the stenosis is performed using coronary angiography using a contrast medium under x-ray control. To do this, a catheter is inserted into the coronary vessel and the contrast medium is injected into the coronary vessel. The catheter is then removed. The disadvantage of this method is that only the diameter of the vessel that can be used by the blood flow, i.e. the narrow part, is shown as a silhouette. An assessment regarding deposits, such as thickness or inflammatory processes, is therefore not possible. The advantage of this solution is in the good image quality of the displayed stenosis.
This is followed by insertion of a balloon catheter under x-ray control to expand the stenosis. The catheter must then be withdrawn again.
This is followed by the insertion again of a catheter to position the stent. After the stent has been positioned, the catheter is again removed. The disadvantage of this method is in the relatively poor visibility of the stent in the x-ray image.
A new image-related method is already in use in some clinics. In this case, an intravascular ultrasound catheter (IVUS) is inserted into the coronary vessels and then withdrawn again from the vessel (“pullback”). This method is, for example, described in publication DE 198 27 460 A1. This catheter provides ultrasound images or profiles of the coronary vessels. Usually, the vessel wall is shown in a 360° cross-section. This method provides important medical information regarding deposits and also an adequate image of the stent. The disadvantage of this method is in the limited resolution of the ultrasound images and that an additional catheter has to be inserted into the coronary vessels.
The disadvantage described above should be avoided with a combination catheter as described in international patent application WO 02/07601, but these images suffer from the relatively poor resolution of the ultrasound method. Various clinical studies failed to determine an improved diagnostic method compared with angiography that would justify the higher price for this solution.
A different solution is described in the not previously published patent application with file reference DE 10 2004 001 498.1. This describes a catheter for insertion into a vessel, comprising a reversible inflatable balloon provided in the area of the catheter point on the outside of which a stent for implanting in the vessel is arranged, and at least one imaging device provided in the area of the catheter tip for optical coherence tomography, that is arranged or designed in such a way that an image can be taken of the vessel area in which the balloon is positioned.
In a further not previously published patent application with file reference DE 103 43 808.4, a medical investigation system and/or treatment system is described that combines the OCT and IVUS imaging methods. This is a combination of two imaging methods that superimpose and display the 2D images. Finally, the likewise not previously published patent application with file reference DE 103 54 496.8 also describes a medical investigation and/or treatment system that combines the OCT and IVUS imaging methods and, additionally, provides a position sensor. In this way, 3D images can be created using two-dimensional imaging methods and position and location information.
Reference is also made to publications U.S. Pat. No. 6,233,476 (Medical Positioning System, Strommer et al.) US 2001/0031919 (Medical Imaging Navigation System, Strommer et al.), US 2002/0049375 (Method and Apparatus for Real Time Quantitative Three-Dimensional Image Reconstruction of a Moving Organ and Intra-body Navigation, Strommer et al.). Document 2002/0049375 represents an improvement on U.S. Pat. No. 6,233,476 and US 2001/003191. The device described there shows the spatial position location of a medical catheter by using magnetic fields, partly in combination with an IVUS sensor. The displayed depth area of the vessels is somewhat limited with these solutions. The stressful insertion of a new catheter is necessary to introduce a stent and again there is some uncertainty in the positioning of the stent.